The R40 has a quite different RTC, with only a single interrupt line, but
two clock outputs. Let's add a compatible.
Acked-by: NChen-Yu Tsai <wens@csie.org>
Signed-off-by: NMaxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: NAlexandre Belloni <alexandre.belloni@bootlin.com>